The idea is to make EV charging easily accessible to encourage people to buy these vehicles. Since cars are parked in employer parking lots much of the day, the ability to charge while at work can potentially double the driving range.

Now, 13 more companies will join them: Coca-Cola, Dell, Facebook, Hertz, AVL, Bentley Systems, Biogen Idec, Bloomberg, Hartford Financial Services Group, National Grid, NRG Energy, Osram Sylvania, Raytheon and Southern California Edison. It's also open to government agencies: The city of Sacramento and New York Power Authority have signed on.

It's part of DOE's EV Everywhere program, announced by President Barack Obama last year, to make plug-ins as affordable and convenient for the American family as gasoline-powered vehicles within the next 10 years.

Electricity is much cheaper to power a vehicle — generally equivalent to about $1 per gallon; these cars need to catch on to make a dent in climate change.